With respect to a welding material, as a rod-shaped welding material (hereinafter referred to as a welding rod), conventionally, there has been known a welding rod which is made of a hard-to-work material such as a Co-based alloy, a Ni-based alloy or an Fe-based alloy. Among these hard-to-work materials, as the Co-based alloy, for example, Stellite (Stellite: registered trade mark owned by Deloro Stellite Holdings Corporation) is known. As the Ni-based alloy, for example, COLMONOY (COLMONOY: registered trade mark owned by Wall Colmonoy corporation), INCONEL (INCONEL: registered trade mark owned by Huntington Alloys Canada Ltd.) and the like are known. As the Fe-based alloy, for example, stainless steel such as JIS D410 is known. Conventionally, as a method for manufacturing a welding rod made of such a hard-to-work material, a method for manufacturing a welding rod by an extrusion method is known (for example, see patent literatures 1 and 2).
Out of these manufacturing methods, the method for manufacturing a welding rod described in patent literature 1 is performed by carrying out the following steps in order. That is, the method for manufacturing a welding rod includes: a compound preparing step in which a compound is prepared by mixing alloy powder made of a hard-to-work material (spheroidal alloy powder of Stellite No. 6) and a binder made of a polybutene binder (thermo plastic resin); an extruding step in which an extruded formed body is prepared by extruding the compound from a forming nozzle at a temperature of 130° C.; a degreasing step in which a binder component is removed from the extruded formed body by heating the extruded formed body prepared in the extruding step (degreasing temperature: 450° C. to 550° C.); and a sintering step in which the extruded formed body from which the binder component is removed in the degreasing step is heated under a vacuum atmosphere (5×10−4 Torr) thus forming a welding rod (sintering temperature: 1280° C.) (see embodiment of patent literature 1).
On the other hand, the method for manufacturing a welding rod described in patent literature 2 is performed by carrying out the following steps in order. That is, the method for manufacturing a welding rod includes: a compound preparing step in which a compound is prepared by mixing alloy powder made of a hard-to-work material (atomized powder of Stellite No. 6 alloy), a binder made of a methylcellulose-based binder and water; an extruding step in which an extruded formed body is prepared by extruding the compound from a forming nozzle; a degreasing step in which a binder component is removed from the extruded formed body by heating the extruded formed body prepared in the extruding step (degreasing temperature: 200° C.); and a sintering step in which the extruded formed body from which the binder is removed in the degreasing step is heated thus forming a welding rod (sintering temperature: 1250° C.) (see embodiment of patent literature 2).
According to the method for manufacturing a welding rod described in patent literature 1 or the method for manufacturing a welding rod described in patent literature 2, a welding rod is manufactured by the extruding method as described above and hence, an elongated welding rod made of a hard-to-work material can be manufactured.